Architect Brad Kennedy explains the geotechnical requirements for building an 80-storey tower on this particular unstable slope. It involves piles 75-metres down to stabilize the slope and balances the tower on more than 100 piles stretching down to bedrock.

Alldritt Group would spend tens of millions of dollars to stabilize the river valley slope before even starting to excavate for its 80-storey tower in The Quarters, the architect said Tuesday.

“This is a serious project that needs a serious foundation,” architect Brad Kennedy said as he tried to answer some of the biggest questions about a plan to build the highest tower in Western Canada above a former coal mine.

The city’s executive committee debated a plan to sell a sloped piece of parkland for the project Tuesday, but did not make a decision. The committee referred the land deal back to administration for two weeks to continue negotiations.

Kennedy said the project team would install a line of concrete piles 1-1/2 metres wide and 75 metres deep along the south edge of Jasper Avenue. Then they’d excavate and install more than 100 piles down to the bedrock.

“You’re essentially balancing the tower on those stilts and in this case there would be well over 100 of them just to hold the tower up,” said Kennedy. “You go down to a level of stabilized substructure, which in our area would be called bedrock. That structure is not subject to slides or slope instability in any way. It’s down 75 metres.”

These geotechnical questions have been top of mind for many in Edmonton — those who know the coal mining history of the area, who can see the marks of successive slumps on that bank and who watched homes fall over a cliff upstream in 1999.

In that case, the homeowners tried unsuccessfully to sue the city for damages.

The land sale is scheduled to return to executive committee Feb. 28 with a rezoning application to be heard at public hearing later.

The Alldritt Group is proposing a thin 80-storey tower at the edge of the river valley on Jasper Avenue west of 96 Street.City of Edmonton /
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Mayor Don Iveson said ongoing negotiations aim to ensure Edmonton can buy back the land if construction falls through. Asked if Edmonton could be liable if it issues a development permit and something goes wrong, Iveson said geotechnical risks are mitigated by technical experts, not politicians.

Similar unstable conditions have been dealt with elsewhere in Edmonton and are part of separate financing and development approval processes, he said. “There is a good risk management system handled by professionals in place today for all of these kinds of issues.”

The 80-storey tower would be worth roughly $250 million and bring an additional $3.2 million a year in taxes, which would go into paying off sewer and other upgrades in The Quarters.

Twenty members of the public spoke for and against the project Tuesday. They argued the view from that section of bank is too precious to lose and a better plan would be to restore it to natural grassland. Other residents argued the tower would be an improvement over garbage and discarded needles.

Some councillors worried the city could increase the height allowed only to see the developer flip the land. But the city could veto any deal under the terms of the land sale, as long as it was not “acting unreasonably.”

“Let me make this clear, we will build this tower,” said David Benjestorf, Alldritt’s general manager of land development, while trying to reassure councillors. The company has already invested millions into developing the legacy project.

It comes with a 10-year sunset clause, returning the land to the city if a minimum 40-storey building doesn’t proceed.

Meanwhile, environmental groups pushed council to adopt a “no net loss” policy, reinvesting proceeds into better parcels to add to the river valley parks.

The Sierra Club has several parcels identified, said representative Charlie Richmond. The parcel Alldritt wants “has close to zero ecological value … This is one of the most modified pieces of land in the entire river valley.”

Harvey Voogd, executive director of the North Saskatchewan River Valley Conservation Society, said he’s opposed to the sale. But if they do sell, proceeds and a third of the taxes should be reinvested.

That’s the only way to show how rare and exceptional a move selling parkland for development is, he said. “Actions speak louder than words.”

Executive committee was told the full land sale agreement, including price, will become public when conditions are removed. That could take up to three years. The land sale would guarantee public access in perpetuity through an easement.

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